How to deal with damp in concrete floors

Date: 25 March, 2019

Safeguard Europe reports on concrete floors, how they can be affected by damp – and the best way to tackle the problem.

Walls are not the only element of a building that is susceptible to damp problems. Floors can be equally as likely to suffer from moisture ingress and penetration. Concrete floors especially can create problems that can be more difficult to solve. Concrete is a naturally very porous material and water can rise up or travel through capillaries which can lead to damp floors and mould issues.

The easiest problems to isolate and repair with damp-floors are issues with above-ground services, such as leaking pipes. Most often these problems can be solved by repairing the source of the moisture and taking the necessary steps to help the damp floor to dry out.

Damp-proof membrane failure

Problems that are more complicated to fix are usually related to damp rising up from the ground and through to the top surface of the concrete. These problems are less common in modern buildings, which are usually constructed using tough plastic damp-proof membranes. Theses membranes are laid onto sand blinding prior to the application of the concrete and, if installed correctly, will stop groundwater from rising through the concrete.

Older buildings, however, were often built without damp-proof membranes and problems with damp floors can arise in these properties. Even newer properties can suffer if the damp-proof membrane was not installed properly or has been punctured.

Problems with damp floors can be tricky to deal with, whether in old buildings or new ones. Using traditional methods, when the physical damp-proof membrane is faulty or entirely missing, the whole floor has to be replaced as identifying the exact location of the defect can be difficult. This is a costly and time-consuming exercise.

There are, however, two options for damp-proofing concrete floors without needing to replace the floor itself. Either a damp-proof coating can be applied to the surface of the concrete or a damp-proof membrane can be laid on top of the concrete.

Damp-proof floor coatings

Most damp-proof floor coatings are applied directly to the concrete floor surface using a brush or roller. Preparation is key with these coatings and the substrate must be sufficiently clean and dry. Which type of coating is chosen will depend on the intended use of the floor.

If the coating is not going to be the final decorative surface and a floor covering will be applied afterwards then a ready-to-use latex-based coating, such as Drybase Liquid Applied DPM, can be used.

For areas where the coating needs to be trafficable, a tougher two-part epoxy coating, such as Drybase ECS Epoxy Floor Coating, should be used. For areas that require a higher chemical resistance, dependent on the intended use, Drybase ECS CR (Chemically-Resistant) Epoxy Coating is available.

Physical damp-proof membranes for concrete floors

Physical damp-proof membranes, such as Oldroyd XS Slimline Membrane, are often quicker and easier to install than using damp-proof coatings as they can be installed on still-damp surfaces. They do, however, always require a separate floor covering on top and special attention needs to be paid to the floor / wall junction detail.

Damp floors will always be a major concern for building owners, but it needn’t be an overly costly or major job to solve with modern methods.